Fig. 5

Immunolocalization of inducible heme oxygenase (HO-1) and constitutive heme oxygenase (HO-2) in placental villi and fetoplacental membranes. Panel (a) shows first trimester villi (7 weeks) and panel (b) shows placental villi at term (37 weeks), stained with anti-HO-1 antibody. Strong staining for HO-1 is localized in the perivascular villous stromal (VS) and weaker staining in trophoblast layer (labelled “T” and arrowhead in panel (a). Panel (c) shows intense staining in the large blood vessels (V) of the stem villi at term (38 weeks). Panels (d-e) show very strong HO-1 staining in the chorio-decidual cells (“C”) and weak staining in the amnion (labelled “A” and arrowhead in panel (e). Panels (f-g) show HO-2 immunoreactivity. Intense staining of the endothelium of the terminal villous capillary bed (C) at term is shown in panel (f). In the endothelium of large blood vessels (g) and the media of the muscularized vessels, there is strong staining for HO-2. Panel (h) shows staining with a-actin in term placenta. Magnifications: 350×, panel c, e, g; 284×, panel a, b, d, f; and 142 ×, panel h.